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Author Topic: Self cocking front exhaust valve  (Read 3848 times))

Offline sb327

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Re: Self cocking front exhaust valve
« Reply #100 on: January 16, 2021, 08:35:14 PM »
I was able to get a little done on last days off in spite of very little shop time.

I got the shuttle made, most of the trigger/disconnect, grip frame and got the swing block functional. (Tp drilled and oring groove cut)

The shuttle rods work like I had hoped. They return the shuttle to adjustable stops. The valve blows open like it should but I need to make a stronger spring for the sear to catch it. I had the same issue with my first all mechanical setup.

Itís taking some shape, just not a very pretty one. I cut a piece of cardboard to cover up some of the ugly and if I squint hard I can see it with a forestock.  :o

Couple of pics

Dave
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Offline Rob M

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Re: Self cocking front exhaust valve
« Reply #101 on: January 16, 2021, 09:05:15 PM »
looks good to me.. soo long as it works as designed
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Offline CableStop

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Re: Self cocking front exhaust valve
« Reply #102 on: January 25, 2021, 10:59:13 PM »
That's some nice machining work.
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Offline sb327

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Re: Self cocking front exhaust valve
« Reply #103 on: January 26, 2021, 09:05:36 AM »
Thanks.

Iíll be home in a couple days so hopefully get to see some progress on this one.

I may print a 1911 style grip for it.

Main thing will be getting all functional parts done and tested. And maybe some more fat trimming on that big chunk.

I may use a trick from the fashion gurus. Something like paint it black and machine a stripe long ways. Give it that slimming appearance......lol

Dave
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Offline sb327

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Re: Self cocking front exhaust valve
« Reply #104 on: February 03, 2021, 04:55:51 PM »
Finally got back to this the last few days. Aesthetically itís better but still ugly as homemade soap to me. But....she functions great and is really fun to shoot.

Part of this project was making a bullet mold. I made it off of Bobís design (thanks again Bob). It weighs in at 43.5 gr.

Iíve got the gun tuned to shoot this at about 800fps.

It doesnít do to bad for an old .22 take off barrel. A little over 1/2Ē group at 50.

The heavier spring took care of the resetting issue I had before. Seems to be rocking along pretty good now.

Plenty left to do on this one but overall am liking it.

Dave
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Offline Rob M

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Re: Self cocking front exhaust valve
« Reply #105 on: February 03, 2021, 05:02:52 PM »
that looks awesome , lots of material removal on that block took place.. can you feel the trigger reset after the shot ?
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Offline sb327

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Re: Self cocking front exhaust valve
« Reply #106 on: February 03, 2021, 06:30:58 PM »
When you pull the trigger, you feel nothing but a regular trigger pull. The shot cycles with no interaction with the trigger due to the fact the valve (being held by sear) trips the disconnector, thereby releasing the trigger from the sear. Once fired however, the disconnector resets with a light Ďclickí, ready for the next shot cycle, upon releasing trigger.

As far as the shuttle coming back into place, I donít notice it at all. It all happens fast.

Kind of a long way of explaining that...lol.

Dave
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Offline rsterne

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Re: Self cocking front exhaust valve
« Reply #107 on: February 03, 2021, 06:32:11 PM »
Nice job, David....  8)

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Offline jackssmirkingrevenge

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Re: Self cocking front exhaust valve
« Reply #108 on: February 04, 2021, 06:48:38 AM »
Coming along nicely!  It would be interesting to see some shot string data to be able to compare the performance to more conventional setups.
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Offline sb327

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Re: Self cocking front exhaust valve
« Reply #109 on: February 04, 2021, 04:26:59 PM »
Thank you guys for the compliments. I appreciate the feedback.

Iíll definitely get the shot data as time allows.

 I may try to make a lighter slug based on Bobs boattail design. I would like to get up to 900fps or so without pushing too hard. Iíve had this up to 65 fpe with current BBT. 43.5gr @ 826fps.

Maybe in the 35 gr range would be about right. ?

 Making molds is a pain in the backside but saves a bunch of money in the long run. Plus, right now, not many molds in stock to choose from.

Dave
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Offline rsterne

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Re: Self cocking front exhaust valve
« Reply #110 on: February 04, 2021, 10:22:05 PM »
The 30 gr. BBT would probably work OK for you.... Your FPE will likely drop a bit with a lighter slug....



or you could make something similar but a bit longer....

Bob
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Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline JuryRigger

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Re: Self cocking front exhaust valve
« Reply #111 on: February 04, 2021, 11:14:03 PM »
Very cool... :D
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Offline sb327

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Re: Self cocking front exhaust valve
« Reply #112 on: February 05, 2021, 09:26:21 AM »
The 30 gr. BBT would probably work OK for you.... Your FPE will likely drop a bit with a lighter slug....



or you could make something similar but a bit longer....

Bob


That looks good to me Bob. I may stretch it just a touch. Iím not concerned about power   at all. I really just referenced the power itís making at present as kind of a idea what itís doing (with reasonable pressure) now. My goal being an accurate slug at 900-950. (Not really sure why, just what I want.... lol)

Thanks again, I appreciate it.
Dave
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Dave